Nor have the life and death decisions he has made on NHS emergency wards for decades put him off his profession.

It was, in the end, his response to an instruction in a nondescript training room that has left his future hanging in the balance.

After being offered a job as a medical assessor for the Department for Work and Pensions (DWP), David was told to refer to those seeking disability allowance as whatever gender they requested.

So, should a man have walked into his office claiming he was a woman, he would need to be treated as such, and described in any correspondence with the pronoun ‘she’ not ‘he’.

In an age in which the Government and the NHS are subjecting transgender issues to ever greater scrutiny, it was an edict that David had been dreading — and one the 55-year-old was unwilling to obey.

‘As a Christian, I believe gender is determined biologically and genetically,’ he says.

He was also very aware that expressing such a belief would be likely to end his career.

‘I was scared, really frightened,’ he admits. ‘I knew it could be the end of my work as a doctor, but I could not live with myself if I didn’t speak up. It would be dishonest — and I didn’t want to live a lie.’

Sure enough, his contract with the DWP was swiftly terminated on the grounds that his refusal to use the preferred pronouns of people who identify as the opposite gender could be considered harassment as defined by the 2010 Equality Act.Three weeks on, he is in little doubt that his career is over.

‘I can’t get a job with any other Government department — doors will be slammed in my face — and I don’t think the NHS will employ me again,’ he says.

‘I am hurt, but relieved I said what I said, because I believe with all my heart that God made us male and female and that I should be allowed to believe this.’

His strong opinions on one of the most divisive subjects of our times are, he insists, not the only issue here. What is also at stake is our right to say what we think without risking our jobs.

‘It is not a question of whether we agree or disagree but whether we are free to say so,’ he says.

‘I’m not out to upset anyone. I care deeply about transgender people. But we must be able to say what we think, and defend what we believe in a non-combative way. Otherwise we will turn into a dictatorial state in which we are all enslaved.’

An unassuming man who relaxes by reading history books and growing tomatoes in his garden in Dudley, West Midlands, David has emerged as an unlikely figurehead for freedom of speech since his ordeal made the news this week.

He fiercely guards his privacy, refusing to divulge any information about his wife and four adult children. He admits he is terrified his unfashionable views may result in him being ‘lynched’.

Perhaps he has good reason to be nervous, given our censorious age in which anyone who dares to deviate from the fashionable consensus that gender is a social construct, not a biological fact, risks being demonised.

Since transgender rights have come to the forefront of public discourse, David says among NHS colleagues a ‘climate of fear’ has emerged regarding new protocols.

Doctors, for example, are now advised by the British Medical Association to use the term ‘pregnant people’ to avoid causing offence to transgender individuals. And, from next year, Government guidelines could require GPs to ask patients’ sexual orientation before each appointment to avoid discrimination.